This invention relates to an apparatus for continuous transfer of powder from a storage tank kept under normal pressure into a high-pressure vessel and to a method for the transfer of powder.
For transfer of powder into a high-pressure vessel, there has generally been employed a lock hopper. Desired transfer of powder into the high-pressure vessel by use of this lock hopper is carried out by a method such as is described below.
First, the powder intended for transfer into the high-pressure vessel and the gas which is required to envelop the received powder inside the high-pressure vessel are introduced into the lock hopper. Then, the lock hopper is locked airtightly and the pressure inside the hopper is increased until it equals the pressure under which the interior of the high-pressure vessel is kept. The hopper is subsequently made to communicate with the high-pressure vessel. Thereafter, the powder conveyor built in the system is manually operated to forward the powder in a required volume from inside the hopper into the high-pressure vessel. To replenish the hopper with the powder, the high-pressure vessel and the lock hopper are separated from each other. After it has been ascertained that the high-pressure gas is not flowing from the vessel into the hopper, the hopper is opened to release the high-pressure gas still remaining therein. Then, the powder is poured into the lock hopper. The air now present inside the lock hopper is displaced with said gas and the pressure inside the lock hopper is again increased, followed by the operation of the powder conveyor. The procedure described above is repeated cyclically.
In this method, the internal pressure of the lock hopper is equalized with that of the high-pressure vessel at the time of delivery of the powder into the high-pressure vessel. If the lock hopper employed in this method happens to be of large dimensions, then quite a large volume of gas should be released from such large lock hopper in order that the internal pressure of the lock hopper may revert to the normal atmospheric pressure. The release of such large volume of gas necessitates either installation of gas holder of considerable size or adoption of a special setup wherein a plurality of smaller lock holders are installed and operated for the pressure of gas to be gradually lowered during the gas' successive flow through said lock holders, whereby the volume of gas to be finally released from the last one of the series of lock holders will be amply decreased and, consequently, the capacity of said gas holder will be minimized.
It follows as a consequence that when the method using such lock hopper is put to practice, it proves to be expensive and entails technical difficulties which prevent the operation from being carried out continuously.
The primary object of the present invention is to provide an apparatus capable of very easily transferring a powder into a vessel maintained under a high pressure without necessitating the release of high-pressure gas which forms an indispensable requirement for effective operation of the known apparatus.
Another object of this invention is to provide a method for easily transferring a powder into a vessel maintained under a high pressure without necessitating the release of high-pressure gas which forms an indispensable requirement for effective operation of the known method.